This invention relates to welding helmets and the controls therefor, and specifically to welding helmets having automatically controlled dark eye shields. More particularly, this invention relates to a welder's helmet in which a dark eye shield is moved automatically into position relative to the welder's mask to protect the welder's eyes against injury from the intense flash of the welding arc. The invention includes controls that ensure that the welding system will not operate when the dark eye shield is in the opened position. The invention also includes means for cooling or ventilating the helmet interior and for defogging the dark eye shield, which is independently controllable by the operator.
There have been many attempts in the past to provide an automatic welder's helmet which will protect the operator's eyes from the intense welding arc during the welding cycle. The intense flash caused by electric arc welding, and tack welding and the like, for example is known to be injurious to the welder's eyes. The typical welder's helmet utilizes a nearly opaque or light radiation absorbing eye piece to block the intense arc light rays. In many instances, the dark eye lens is permanently affixed to the welder's helmet in such a manner that the operator must continuously manually raise and lower his helmet in order visually inspect his work. In other cases, the helmet is mounted on a head gear which permits the operator to manually flip up or slide up vertically or otherwise move the eye piece to see his work. When the welder is required to either remove the welding helmet or to manually flip up or slide up or otherwise open the eye piece, this has greatly reduced his efficiency in the welding operation. Therefore, many attempts have been made to automate the opening and closing of the dark eye shield.
One such prior art attempt is disclosed in U.S. Pat. No. 3,096,430 issued July 2, 1963 to R. S. Farr. This patent discloses a pneumatically operated eye shield which is pivotally mounted on the helmet and is opened and closed by a pneumatic cylinder. The associated electrical circuitry for controlling the welding system and the dark eye shield control unit utilizes a time delay relay in order to assure that the welding arc cannot be struck until the dark eye shield is closed. However, no provision is made in this device for assuring that the arc has completely ceased before the dark lens is opened.
A more recent attempt to provide an improved automatic welder's helmet is disclosed in U.S. Pat. No. 4,293,756 which was issued on Oct. 6, 1981 to Francis J. Niemi. The helmet disclosed in this patent is equipped with an automatic control for controlling the helmet's dark eye shield prior to energizing the electrode for striking the welding arc, and further to maintain the dark eye shield closed until after the arc and the weldment's light afterglow have ceased. The helmet also includes a ventilation system which operates to ventilate the helmet and to remove annoying welding fumes and smoke from the interior of the helmet, and especially about the eye shield itself in its lowered position on the operator's head. In one embodiment, the ventilation system operates only when the operator is using the welding system.
One major disadvantage of the helmet disclosed in the above Niemi patent is the complexity of the system for raising and lowering the dark eye shield. The dark eye shield is raised and lowered by an air cylinder which has a piston rod or shaft. This shaft is joined in the center of a yoke. The system includes a pair of guide members with appropriate guides for operation of the yoke. Such a complex system is not only expensive to manufacture, but also adds considerable weight to the helmet, which increases the fatigue of the welder using the helmet. Yet another disadvantage to the helmet of Niemi is that the ventilation system is operated automatically and does not take into consideration the individual needs of a welder. In some environments, the welder may desire more ventilation than in others, and in other environments the welder may desire to have no ventilation at all. The helmet disclosed in the Niemi patent does not permit such individual choices to be made.
Another problem is found in prior automatic welder's helmets, in that, they often allow the protective lens to be accidentally opened while the welding operation continues. Additionally, there has been the continual problem of buildup of unwanted heat and welding fumes within the welder's helmets during long periods of welding, especially when the welding is being performed on preheated fabrications. Furthermore, there is a need to protect welders who are careless and who do not properly utilize the protective helmet.
The present invention overcomes the foregoing and other problems inherent in the prior art by utilizing in the control for the welding system means to prevent commencement of welding until exhaustion of the pneumatic cylinders which automatically permits springs associated with the pneumatic cylinders to close the dark eye lens. Closing of the lens completes the circuitry for the welder. When the lens is lowered, either accidently or intentionally by the welder. As soon as the lens begins to open, the circuitry for the welding system is disconnected.
A time delay relay is preferably interposed within the circuit for actuating the mechanism for opening the dark eye lens. Consequently, the dark eye lens cannot be opened until a predetermined preset interval has expired after the circuitry for the welding system has been interrupted.
It will be seen that the automatic welder's helmet of the present invention provides protection for the welder's eyes, helps to ventilate, cool and defog the helmet's interior and lenses in accordance with the welder's desires; and increases welder productivity by eliminating welder down time. Furthermore, the present invention offers a simple and inexpensive construction, which is both lightweight and easy to use, and which due to the construction of same permits full view by the welder.
It is therefore an important object of the present invention to provide an automatic welder's helmet having a pneumatic operated dark eye shield which prevents welding when the dark eye shield is in the opened position.
It is another object of the present invention to provide an automatic welder's helmet with individually operated, manually controlled, interior ventilation means for eliminating fumes which collect in the helmet and for providing a fresh supply of air.
It is a further object of the invention to provide electrical and pneumatic control means for an automatic welder's helmet in which there is a switch means that is actuated when the dark eye lens is closed to permit the welding system becomes operable, and there is a time delay means included which is actuated when the welding system is rendered inoperable and before the dark eye lens is permitted to open.